The community diversity and CO2 emission flux of Deyeuxia angustifolia wetland were investigated by using static box method, in order to understand the relationship of the community diversity and CO2 emission and nitrogen deposition concentration in the Deyeuxia angustifolia marsh meadow wetland of Sanjiang Plain. The results showed that high nitrogen significantly increased the Shannon-Wiener index of the Deyeuxia angustifolia wetland, but low nitrogen decreased the Shannon-Wiener index of the Deyeuxia angustifolia wetland. High nitrogen significantly inhibited the dominance index of Deyeuxia angustifolia wetland, low nitrogen also decreased the dominance index of Deyeuxia angustifolia wetland. High nitrogen significantly increased the evenness index of Deyeuxia angustifolia wetland, although low nitrogen also increased the evenness index of Deyeuxia angustifolia wetland, but the difference was not significant. The mean value of CO2 emission fluxes was 411.79 in the Deyeuxia angustifolia wetland and 607.50 in the low-nitrogen, while in the high-nitrogen, the mean value of CO2 emission flux was 607.50. The average CO2 emission flux was 608.86, so nitrogen application significantly increased the CO2 emission flux, but there was no significant difference between low nitrogen and high nitrogen treatment.